[whatwg] XML databases, XML syntax and HTML5

Elliotte Harold elharo at metalab.unc.edu
Sat Dec 9 02:55:54 PST 2006

Benjamin Hawkes-Lewis wrote:

> Can I ask some really basic questions about this? (Jason Hunter's talk
> didn't appear to be online.) Are there Exist equivalents for Python,
> PHP, and Ruby programmers, or do we all need to use Java in the brave
> new world?

For eXist I don't know. However the major payware systems (Db 2 9, Mark 
Logic, Oracle, etc.) all are essentially language neutral, just as SQL 
databases are. They have bindings for all major languages.

Open source offerings are a little thin on the ground right now, and not 
as robust as I'd like, but that's going to change, possibly by the end 
of next year if not sooner.

> Is the theory here that the entire site's content goes into one XML
> file? 

No. We're using a database, not a file system. XML documents go into the 
database, but there are many such documents. One per page, one per 
sidebar, one per comment, whatever. You can organize the content to fit 
your site.

> And, if so, what happens when it gets big? 

If that happens, you're a lot better off with a database store than a 
filesystem. The databases can vastly outperform file system based 
XSLT/XQuery processors like Saxon for large files due to indexing, by an 
order of magnitude or more. It's probably not really relevant for web 
sites, where the documents just aren't just that big.  But if you're 
working on airplane technical manuals and encyclopedias and such, the 
difference is very impressive.

> Or would you have
> different XML files for each article, comment, and user? What happens to
> hypermedia like videos, images, and audio? 

In hybrid systems like DB 2 9, you'd probably put some of that data, 
like the users, in a classic SQL table. Binary data can be stored in the 
file system (like WordPress does today) or as a BLOB in the database. 
Some of these details do change from one database to the next. For 
instance, Mark Logic allows you to store plain text, blobs, and XML 
documents right in the database, with XQuery extensions for manipulating 
this stuff.

> Are such systems going to be as simple for
> end-users to install on their servers as WordPress?

Depends on who writes them, I suppose. eXist replaces MySQL, not 
WordPress. No reason such a system can't be equally easy to install.

Elliotte Rusty Harold  elharo at metalab.unc.edu
Java I/O 2nd Edition Just Published!

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